"Stripping the sultan of the honours they have bestowed upon him would send out the important message that they do not wish to be in any way associated with this sort of medieval barbarism," Evans added.

The Queen and Bolkiah in Bandar Seri Begawan, Brunei's capital, on September 17, 1998. Reuters

Bolkiah was made an honorary admiral in the Royal Navy in 2001. He was also made an honorary air chief marshal in the Royal Air Force, awarded by the Queen.

The decision to award Bolkiah the honors was not made by the Queen herself, Buckingham Palace told Business Insider.

Celebrities have stoked a viral campaign to boycott nine hotels owned by the Sultan, one of the richest heads of state, worth about $20 billion. It reached a peak on Thursday when eight deleted their Twitter profiles.